Aging of the erythrocyte. X. Immunoelectrophoretic studies on the denaturation of superoxide dismutase.

Superoxide dismutase (SOD) content estimated by rocket immunoelectrophoresis did not differ in various density (age) fractions of bovine erythrocytes though its specific activity decreased with increasing cell density. No changes were found, either, in the crossed immunoelectrophoretic pattern of SOD with increasing red cell age. Effects of different denaturing agents on the immunoelectrophoretic pattern and activity of the enzyme were compared, including H2O2 and free radicals generated by ionizing radiation. The yield for inactivation was higher than that for loss of antigenic properties in all cases studied which could correspond to the in vivo situation. However, changes in electrophoretic mobility were revealed for all the denaturing agents, which is contrary to a main causative role of these agents in the in vivo inactivation of SOD. The results suggest spontaneous "subtle denaturation" as a chief cause for the SOD inactivation during erythrocyte aging.